1. Field of Invention
This invention relates to a method and apparatus for allowing a service switching point (SSP) to route to a remote Intelligent Peripheral (IP) without the need to requery a service control point (SCP).
2. Description of Related Art
Currently, under Advanced Intelligent Network (AIN) requirements, calls are routed to IPs at the behest of the service control point (SCP) when speech services are needed for service processing. These speech services include playing announcements and collecting digits from a calling/called party. The SSP routes the appropriate message to the IP to set up the call. If the IP returns an error, the SSP will not have knowledge of the type of error. The error type is passed transparently to the SCP and the SCP must again determine the remote IP criteria. Thus, the SSP will requery the SCP every time the SSP attempts to route to an IP and the attempt fails. The querying and requerying is very costly in time, i.e., post dial delay, and message traffic to the entire network.
This invention provides for an IP routing system and method that allows a switch to control the routing to a special applications device which results in savings of time, cost and capacity throughout the entire network. Control of the routing lies within the switch, thus reducing the need to requery a controller in error situations. For example, the switch will know if an alternate route to a special applications device is possible if an error message is received from the special applications device without requerying to the controller. For the sake of illustration, the switch can be an originating SSP, the controller a SCP, and the special applications device can be an IP.
As one example, when the originating SSP receives a call, a trigger is activated. Based on the trigger, the originating SSP sends a message to the SCP. The SCP receives the message from the SSP and determines which service is appropriate for the call. If it is determined, for example, that an announcement is to be played and digits are to be collected from a caller, the SCP will send a message back to the originating SSP. The message sent to the originating SSP includes a destination address that enables the originating SSP to route the call to an IP. Routing to a remote IP is a scheme used by the originating SSP to access remote IP capabilities that are not otherwise available at the originating SSP at which the call originated.
The originating SSP receives the message from the SCP and extracts the destination address and determines if the address represents a locally connected IP or if the originating SSP has to route through the network to the IP. If it is a locally connected IP, the SSP then sends a message to the local IP for the purpose of setting up a connection and for delivering call control information. At this point there are two error possibilities. The originating SSP could find that it cannot route to the local IP due to the connection not being available to the local IP or the local IP cannot process the request. Ordinarily, if an error occurred, conventional SSPs would return a message to the SCP; and based on the type of error reported, the service processing at the SCP would make a decision to either clear the call or request another IP. However, the present invention allows the SSP to make a decision, without requerying to the SCP, to either clear the call or request another IP.
Thus, when the SCP requests the SSP to route to an IP, the SCP can send the appropriate destination address to the SSP so that the SSP would have access to several routes in a Remote IP Routing Table. The first route can be to a local IP. When the SSP attempts to utilize this first route and it fails, the SSP can automatically access the second route in the table without requerying the SCP. If the second route fails, the SSP can try the third route and so on. This reduces substantial post dial delay, saves SSP and SCP capacity, and cuts down on network traffic by not having to requery the SCP for each route failure. Thus, the SSP may actually get the opportunity to try a third or fourth route whereas, under conventional AIN processing, the second route might be the last route practical due to post dial delay.
These and other aspects of the invention will be apparent or obvious from the following description.